The general objective of this research is to determine the role of the spectral environment during early visual experience, and thus extend our knowledge of how the sensory environment modifies the developing nervous system. From previous research, we know that appropriate sensory input early in life is critical to the development of normal spatial vision and binocular vision. Little work has been done to determine to what extent the spectral composition of the lighting environment may influence normal visual development. Two visual functions that should rely heavily on spectrally-normal lighting environments are spectral sensitivity and color vision. Behavioral methods will be used to assess increment-threshold spectral sensitivity and color vision in normal animals and in animals reared in spectrally-restricted visual environments (e.g., red light, sometimes in combination with monocular pattern deprivation). Single-unit electrophysiological data will be obtained from these same animals to assess the impact of the rearing environment at the cell systems level. Three hypotheses will be addressed: 1) That the development of normal color vision has a post-natal component that depends on adequate visual stimulation of each cone type, and that this requirement is normally fulfilled by exposure to a spectrally- balanced "full-spectrum" lighting environment. 2) That this criterion stimulation must occur during certain "critical periods" of visual development, which may or may not correspond to the critical periods for normal development of other visual functions. 3) That the stimulus deprivation syndrome used as an animal model to study mechanisms of human amblyopia, when produced in monkey by monocular lid-suture, is a complex effect that is due to both the lack of contours on the retina, and the unbalanced spectral stimulation produced by the eyelid's acting as a long-pass chromatic filter.